tools/testing/selftests/vm/gup_benchmark.c: add MAP_HUGETLB option

Add a new option '-H' to the gup benchmark to help understand how hugetlb
mapping pages compare with the default.

Link: http://lkml.kernel.org/r/20181010195605.10689-6-keith.busch@intel.comSigned-off-by: NKeith Busch <keith.busch@intel.com>
Reviewed-by: NAndrew Morton <akpm@linux-foundation.org>
Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

tools/testing/selftests/vm/gup_benchmark.c

@@ -36,7 +36,7 @@ int main(int argc, char **argv)
 	char *file = "/dev/zero";
 	char *p;
 
-	while ((opt = getopt(argc, argv, "m:r:n:f:tTLUS")) != -1) {
+	while ((opt = getopt(argc, argv, "m:r:n:f:tTLUSH")) != -1) {
 		switch (opt) {
 		case 'm':
 			size = atoi(optarg) * MB;
@@ -69,6 +69,9 @@ int main(int argc, char **argv)
 			flags &= ~MAP_PRIVATE;
 			flags |= MAP_SHARED;
 			break;
+		case 'H':
+			flags |= MAP_HUGETLB;
+			break;
 		default:
 			return -1;
 		}